Central apnea and hypopnea stem from insufficient central nervous system drive and result in inadequate ventilation. Many of those afflicted also suffer from congestive heart failure (CHF). A particular form of apnea and hypopnea is known as Cheyne-Stokes Respiration (CSR), in which tidal volume oscillates between hyperpnea and hypopnea and/or apnea with a periodicity on the order of about 70 seconds. In general, CSR occurs during sleep and therefore CSR can preclude quality sleep through induction of apnea-terminating arousals. CSR also burdens the heart with transient episodes of hypoxia and surges in sympathetic tone, which can exacerbate CHF.
Various studies have examined how respiratory therapy may benefit CHF patients that experience CSR. For example, a study by Sin et al., “Effects of continuous positive airway pressure on cardiovascular outcomes in heart failure patients with and without Cheyne-Stokes respiration”, Circulation, 102: 61-66 (2000), indicates that continuous positive airway pressure improves cardiac function in patients with CHF who also have CSR and central sleep apnea. In particular, this study indicated that continuous positive airway pressure improved left ventricular ejection fraction and resulted in a risk reduction in the mortality-cardiac transplantation rate. However, the approach taken by Sin et al. relies on an external pressure generating device that provides positive airway pressure. As discussed herein, various techniques to terminate respiratory oscillation characteristic of CSR may be implemented using an implantable device that may optionally provide cardiac therapy as well.